This invention relates generally to a method and apparatus for producing image data by data processing and, more particularly, to a new and improved image data processing method and apparatus for processing enhanced image data, and a recording medium carrying such enhanced image data.
It is common practice in the prior art that images produced on a television receiver, a monitor or a CRT display of a home video-game machine, a microcomputer, or a graphic computer are substantially two-dimensional. Such images are usually animated by moving and varying a two-dimensional character or object on a planar two-dimensional background. However, such two-dimensional images or pictures are limited in both the modeling of a background and the movement of character objects, thus failing to yield more realistic images, particularly in a video game.
For improvement, various methods of making highly realistic three-dimensional images or pictures have been proposed and some of them are described below. One of various predetermined movements of a character object viewed from several directions may be selected and displayed according to visual variation, such as a change in the viewpoint in the image. Also, a simulated three-dimensional image may be created by overlapping a plurality of two-dimensional graphics, one over the other, in a depthwise direction. A texture mapping method may also be provided in which the surfaces of a polygon are filled with a texture map (of material or pattern) to generate an image model. In another method, a variation of colors is produced by changing color data of the image with the use of a color lookup table.
In a typical example of a prior art home video-game machine, manipulation information is introduced from an input device, such as an entry pad or a joy stick, and is passed across an interface along a main bus by the action of a CPU consisting mainly of a microprocessor. Upon introduction of the manipulation data, three-dimensional data stored in a main memory is transmitted by the action of a video processor to a source video memory for temporary storage.
The aforementioned CPU also operates to transfer to the video processor a specific sequence for reading out a series of image data segments from the source video memory for overlapping them, one over the other, on the screen. According to the reading sequence of the image data segments, the video processor reads the image data segments from the source video memory and displays them in their overlapped arrangement.
While the image data segments are being read and displayed, audio components of the manipulation information are fed to an audio processor which, in turn, picks up corresponding audio data from an audio memory for synchronization with the image data.
For example, the source video memory may hold a background of a checker-board pattern and a group of rectangular image segments or sprites representing cross sections of a cylindrical object in the background. Other areas besides the cross sections of the cylindrical object on the sprites may be drawn in transparency.
A sync generator mounted in the video processor generates a read address signal in response to a sync signal of the image data. The read address signal of the sync generator is transmitted via the main bus to a read address table determined by the CPU. The sync generator also reads the image segments from the source video memory in response to a signal from the read address table.
The video data segments retrieved are then fed to an overlap processor where they are overlapped, one over the other, in the sequence determined by a priority table and passed via the main bus from the CPU. Since the background comes first and is then followed by the rectangle sprites, the group of sprites are placed in superposition, one over the other, on the background.
Then, the other areas in addition to the cross sections of the cylindrical object of the aforementioned sprites, which are overlapped one over the other on the background, are rendered to transparency by a suitable transparency processor. As a result, the two-dimensional image data of the cylindrical object can be reproduced as three-dimensional data VD0 of the original image.
The source video memory is divided into two areas: a pixel data storage area, in which pixel data are aligned in a two-dimensional arrangement expressed by a matrix of small squares, and a color lookup table area, in which color data are aligned in a one-dimensional arrangement denoted by a row of small rectangles.
The color lookup table comprises a one-dimensionally aligned color data table extending in one direction or laterally of the source video memory. The color lookup table thus depends much on the lateral distance of the source video memory and will be limited in the number of colors that can be displayed.
Accordingly, there has been a long existing need for enhanced image data processing offering a greater number of colors, compatible with relatively simple processing, and for a recording medium carrying such enhanced image data. The present invention clearly fulfills these needs.